1. Field of the Invention
This invention pertains to cleaning methods for electrostatic chucks.
2. Description of the Related Art
Semiconductor manufacturing apparatus such as sputtering apparatus is generally equipped with a low-pressure chamber, wherein is disposed a substrate support equipment to support a substrate such as a semiconductor wafer. The substrate support equipment is equipped with a base member that contains a heater or a cooler, and an electrostatic chuck, equipped on top of the base member, to which a voltage is applied to adhere and hold the semiconductor wafer through a coulomb force.
In semiconductor wafer processing using this type of substrate support equipment, processes such as the fabrication of metal films on the semiconductor wafer using, for example, sputtering processes, are performed after the semiconductor wafer is adhered to the electrostatic chuck. However, contaminants adhere to, and accumulate on, the electrostatic chuck as the semiconductor wafer process is performed repeatedly. As the contaminants accumulate, the force by which the electrostatic chuck is able to adhere the semiconductor wafer is weakened, leading to the risk that the wafer may shift out of position. Consequently the electrostatic chuck must be cleaned to remove the contaminants each time the semiconductor wafer process, is repeated a specific number of times.
Although a process of opening the chamber and manually wiping with a solvent to remove contaminants from the electrostatic chuck can be envisioned as a method for cleaning the electrostatic chuck, this method requires the chamber to be opened and the electrostatic chuck to be cooled to about room temperature, thus making the removal of the contaminants require an extended period of time, preventing the cleaning process from being performed efficiently.
In contrast, a method known as “cycle purging,” wherein the contaminants are removed by the flow of the bulk gas by repetitively venting the bulk gas in the chamber and then drawing a rough vacuum, has been envisioned as a method for cleaning the Cleo electrostatic chuck without opening the chamber. As the result of researching the conventional technologies described above, the inventors discovered challenges as described below. In other words, even in a cleaning method using cycle purging, described above, the electrostatic chuck must still be cooled to a temperature of 100° C. or below when the cleaning is performed, so the removal of the contaminants still takes time, preventing efficiency in the cleaning, and it has not been possible to remove the contaminants adequately from the electrostatic chuck.
Given this, the object of this invention is to provide an electrostatic chuck cleaning method wherein the removal of contaminants from the electrostatic chuck is performed both efficiently and completely.